[2] The county was founded in 1884 and is named for John C. Frémont, a general, explorer, and politician.

Fremont County comprises the Riverton, WY Micropolitan Statistical Area.

Fremont County was named for John Charles Frémont, an explorer of the American West, United States Senator from California, and 1856 Republican presidential candidate.

[4][5] Fremont County is the site of the Wind River Indian Reservation, home of the Eastern Shoshone and Northern Arapaho tribes of Native Americans.

Although the county seat is Lander, the largest community is Riverton, home of Central Wyoming College and the economic hub of the region.

A large portion of the western edge of the county follows the Continental Divide at the crest of the Wind River Range of the Rocky Mountains, known for its wilderness areas and home of the largest glaciers in the American Rocky Mountains.

As of the 2000 United States census,[10] there were 35,804 people, 13,545 households, and 9,481 families in Fremont County.

As of the 2010 United States census, there were 40,123 people, 15,455 households, and 10,360 families residing in the county.

[16][17] Both facilities were operated by the Wyoming Board of Charities and Reform until that agency was dissolved as a result of a state constitutional amendment passed in November 1990.

In his poem The Ballad of Jesus Ortiz, Dana Gioia describes how his great-grandfather, a Mexican immigrant from Sonora, worked as a Wild West cow-puncher and was later murdered by a disgruntled and racist patron while working as a saloon keeper in the Fremont County town of Lost Cabin, Wyoming in 1910.

Scenes from the movie Taking Chance were set in Dubois, a town within Fremont County.

The real-life Chance Phelps from the film was born in Riverton and is buried in Dubois, both in Fremont County.